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From:   "Jason A. Donenfeld" <Jason@zx2c4.com>
Date:   Wed, 23 Dec 2020 17:12:26 +0100
Message-ID: <CAHmME9oDA1ch3_3EdVhEHAE5Rk7QxMwS8g9e87aet_8ohEJ3Gw@mail.gmail.com>
Subject: Re: drivers/char/random.c needs a (new) maintainer
To:     Petr Tesarik <ptesarik@suse.cz>
Cc:     Torsten Duwe <duwe@lst.de>,
        Marcelo Henrique Cerri <marcelo.cerri@canonical.com>,
        "Theodore Y. Ts'o" <tytso@mit.edu>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        =?UTF-8?Q?Stephan_M=C3=BCller?= <smueller@chronox.de>,
        Willy Tarreau <w@1wt.eu>,
        Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
        Nicolai Stange <nstange@suse.de>,
        LKML <linux-kernel@vger.kernel.org>,
        Arnd Bergmann <arnd@arndb.de>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        "Alexander E. Patrakov" <patrakov@gmail.com>,
        "Ahmed S. Darwish" <darwish.07@gmail.com>,
        Matthew Garrett <mjg59@srcf.ucam.org>,
        Vito Caputo <vcaputo@pengaru.com>,
        Andreas Dilger <adilger.kernel@dilger.ca>,
        Jan Kara <jack@suse.cz>, Ray Strode <rstrode@redhat.com>,
        William Jon McCann <mccann@jhu.edu>,
        zhangjs <zachary@baishancloud.com>,
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        Florian Weimer <fweimer@redhat.com>,
        Lennart Poettering <mzxreary@0pointer.de>,
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        Dan Carpenter <dan.carpenter@oracle.com>,
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        Eric Biggers <ebiggers@kernel.org>,
        Ard Biesheuvel <ardb@kernel.org>, simo@redhat.com
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On Wed, Dec 23, 2020 at 5:03 PM Jason A. Donenfeld <Jason@zx2c4.com> wrote:
>
> Hi Peter,
>
> On Wed, Dec 23, 2020 at 5:01 PM Petr Tesarik <ptesarik@suse.cz> wrote:
> > I never suggested that this should serve as a supportive argument. I was just trying to be honest about our motivations.
> >
> > I'm a bit sad that this discussion has quickly gone back to the choice of algorithms and how they can be implemented.
>
> Why are you sad? You are interested in FIPS. FIPS indicates a certain
> set of algorithms. The ones most suitable to the task seem like they'd
> run into real practical problems in the kernel's RNG.
>
> That's not the _only_ reason I'm not keen on FIPS, but it does seem
> like a very basic one.
>
> Jason

And just to add to that: in working through Nicholai's patches (an
ongoing process), I'm reminded of his admonishment in the 00 cover
letter that at some point chacha20 will have to be replaced, due to
FIPS. So it seems like that's very much on the table. I brought it up
here as an example ("For example, " is how I began that sentence), but
it is a concern. If you want to make lots of changes for cryptographic
or technical reasons, that seems like a decent way to engage. But if
the motivation for each of these is the bean counting, then again, I'm
pretty wary of churn for nothing. And if that bean counting will
eventually lead us into bad corners, like the concerns I brought up
about FPU usage in the kernel, then I'm even more hesitant. However, I
think there may be good arguments to be made that some of Nicholai's
patches stand on their own, without the FIPS motivation. And that's
the set of arguments that are compelling.

Jason